Our invention relates to the addition of precise amounts of a plurality of non-compatible substances into a mixing zone. More specifically, our invention relates to adding polymer additives and catalyst deactivation agents into a monomer polymerization process.
In a variety of chemical processes a plurality of substances must be added to a mixing zone in precise amounts during the operation of the process. If the various substances are compatible with each other, that is, soluble in each other or a common solvent, a simple solution of these substances may be injected into the mixing zone. However, if the substances are non-compatible with each other, substantial difficulties are encountered. For example, if some non-compatible substances are soluble only in an organic solvent while others are insoluble in such solvents, a traditional method of adding these types of materials to a mixing zone is to inject each substance separately. This method of multiple input streams can lead to problems in metering and controlling the precise amount of each substance entering the zone. In addition, insoluble components cannot be easily added by this method. Since the amounts of each entering component may vary over the course of a process or between different runs of the process, a non-uniform product can result. Further, since each substance, which may or may not react chemically with other materials present, is being added separately, incomplete mixing can occur with all reactive species present in the zone, thus causing an inefficient process of non-uniform product. Although the non-compatible substances can be liquids or even gases, these problems are especially acute when one or more of the entering substances is a solid.
More specifically, in monomer polymerization processes such as the catalytically promoted polymerization of alpha-olefins including ethylene, propylene and copolymers thereof, additives such as a polymer stabilization package, coloring agents, and a catalyst kill and/or deactivation package are added usually during the later stages of the process. The exact point of addition in the process will vary from process to process with the preferred addition point being established by those skilled in the art. These polymer additives and catalyst deactivation agents are liquids, solids and sometimes gases, and can vary from soluble to insoluble in water or in organic solvents. Since there is no single solvent that will sufficiently dissolve all of the required components in such processes, the current practice is to inject these additives and agents into the reaction process through multiple input streams, or to add them in master batches in powder form. In either of these methods, it is difficult to meter the additions with precision and especially it is extremely difficult to add solids to a polymer in a melting zone.
The general object of our invention is to provide a method of simultaneously injecting controlled amounts of a plurality of non-compatible substances into a mixing zone. Another object is to provide a composition in which a plurality of non-compatible substances may be carried into a mixing zone. A specific object of our invention is to provide a method of introducing polymer additives and catalyst deactivation agents into a monomer polymerization process. Other objects will appear hereafter.